The present invention relates in general to the display of characters on a television receiver and, more particularly, to an apparatus for preventing the simultaneous display and overlapping of teletext characters and on-screen display characters on a television receiver.
In general, conventional TV receivers have a teletext (TTX) processor and/or an on-screen display (OSD) system. A TTX processor displays characters, simple figures, etc. based on an information signal received with the television carrier wave. At the same time, an OSD system displays characters and the like on the TV receiver screen to inform the user of changes in the presently performing functions of the TV, for example, a change of volume or channel.
However, conventional TV receivers having both the TTX processor and OSD system suffer from drawbacks in that TTX characters and OSD characters overlap when displayed so that the viewer cannot recognize either of the displayed characters. That is, if the user changes, for example, the volume of the TV while the TTX processor is displaying characters both TTX characters and OSD characters are mixed making it very difficult, if not impossible to discern the characters.
Further, such conventional TV receivers have the further disadvantage in that while TTX characters and OSD characters are displayed at the same time, the oscillating frequency of an oscillator driving a TTX data generating unit and the oscillating frequency of an oscillator driving an OSD data generating unit are not synchronized, thereby giving rise to a flicker of the displayed characters.